Liquid crystal composition and liquid crystal display device

ABSTRACT

To provide a liquid crystal composition satisfying at least one or having a suitable balance regarding at least two of characteristics such as high maximum temperature of a nematic phase, low minimum temperature thereof, small viscosity, suitable optical anisotropy, large negative dielectric anisotropy, large specific resistance, high stability to ultraviolet light and heat; and an AM device having characteristics such as short response time, a large voltage holding ratio, low threshold voltage, a large contrast ratio and a long service life. A liquid crystal composition has negative dielectric anisotropy and a nematic phase, and contains a compound contributing to high stability to heat or ultraviolet light. The composition may contain a specific compound having large negative dielectric anisotropy as a first component, a specific compound having high maximum temperature or small viscosity as a second component, and a specific compound having a polymerizable group.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefits of Japanese applicationserial no. 2014-108149, filed on May 26, 2014 and Japanese applicationserial no. 2014-232358, filed on Nov. 17, 2014. The entirety of each ofthe above-mentioned patent applications is hereby incorporated byreference herein and made a part of this specification.

TECHNICAL FIELD

The invention relates to a liquid crystal composition, a liquid crystaldisplay device including the composition, and so forth. In particular,the invention relates to a liquid crystal composition having a negativedielectric anisotropy, and a liquid crystal display device including thecomposition and having such a mode as an IPS mode, a VA mode, an FFSmode and an FPA mode. The invention also relates to a liquid crystaldisplay device having a polymer sustained alignment mode.

BACKGROUND ART

In a liquid crystal display device, a classification based on anoperating mode for liquid crystal molecules includes a phase change (PC)mode, a twisted nematic (TN) mode, a super twisted nematic (STN) mode,an electrically controlled birefringence (ECB) mode, an opticallycompensated bend (OCB) mode, an in-plane switching (IPS) mode, avertical alignment (VA) mode, a fringe field switching (FFS) mode and afield-induced photo-reactive alignment (FPA) mode. A classificationbased on a driving mode in the device includes a passive matrix (PM) andan active matrix (AM). The PM is further classified into static,multiplex and so forth, and the AM is classified into a thin filmtransistor (TFT), a metal insulator metal (MIM) and so forth. The TFT isfurther classified into amorphous silicon and polycrystal silicon. Thelatter is classified into a high temperature type and a low temperaturetype according to a production process. A classification based on alight source includes a reflective type utilizing natural light, atransmissive type utilizing backlight and a transflective type utilizingboth the natural light and the backlight.

The liquid crystal display device includes a liquid crystal compositionhaving a nematic phase. The composition has suitable characteristics. AnAM device having good characteristics can be obtained by improvingcharacteristics of the composition. Table 1 below summarizes arelationship between characteristics in two aspects. The characteristicsof the composition will be further described based on a commerciallyavailable AM device. A temperature range of the nematic phase relates toa temperature range in which the device can be used. A preferred maximumtemperature of the nematic phase is approximately 70° C. or higher and apreferred minimum temperature of the nematic phase is approximately −10°C. or lower. Viscosity of the composition relates to a response time inthe device. A short response time is preferred for displaying movingimages on the device. A shorter response time even by one millisecond isdesirable. Accordingly, a small viscosity in the composition ispreferred. A small viscosity at a low temperature is further preferred.

TABLE 1 Characteristics of Composition and AM Device No. Characteristicsof Composition Characteristics of AM Device 1 Wide temperature range ofa Wide usable temperature range nematic phase 2 Small viscosity Shortresponse time 3 Suitable optical anisotropy Large contrast ratio 4 Largepositive or negative Low threshold voltage and dielectric anisotropysmall electric power consumption Large contrast ratio 5 Large specificresistance Large voltage holding ratio and large contrast ratio 6 Highstability to ultraviolet Long service life light and heat

An optical anisotropy of the composition relates to a contrast ratio inthe device. According to the mode of the device, a large opticalanisotropy or a small optical anisotropy, more specifically, a suitableoptical anisotropy is required. A product (Δn×d) of the opticalanisotropy (Δn) of the composition and a cell gap (d) in the device isdesigned so as to maximize the contrast ratio. A suitable value of theproduct depends on a kind of the operating mode. The value is in therange of approximately 0.30 micrometer to approximately 0.40 micrometerin a device having the VA mode, and in the range of approximately 0.20micrometer to approximately 0.30 micrometer in a device having the FFSmode. In the above case, a composition having a large optical anisotropyis preferred for a device having a small cell gap. A large dielectricanisotropy in the composition contributes to a low threshold voltage, asmall electric power consumption and a large contrast ratio in thedevice. Accordingly, the large dielectric anisotropy is preferred. Alarge specific resistance in the composition contributes to a largevoltage holding ratio and a large contrast ratio in the device.Accordingly, a composition having a large specific resistance at roomtemperature and also at a high temperature in an initial stage ispreferred. A composition having a large specific resistance at roomtemperature and also at a high temperature even after the device hasbeen used for a long period of time is preferred. Stability of thecomposition to ultraviolet light and heat relates to a service life ofthe device. In the case where the stability is high, the device has along service life. Such characteristics are preferred for an AM devicefor use in a liquid crystal projector, a liquid crystal television andso forth.

A liquid crystal composition containing a polymer is used in a liquidcrystal display device having a polymer sustained alignment (PSA) mode.First, a composition to which a small amount of polymerizable compoundis added is injected into a device. Next, a composition is irradiatedwith ultraviolet light while voltage is being applied between substratesof the device. The polymerizable compound polymerizes and generates apolymer network structure in the composition. In the composition,alignment of liquid crystal molecules can be controlled by the polymer,and therefore response time of the device is shortened and imagepersistence is improved. Such an effect of the polymer can be expectedfor the device having a mode such as the TN mode, the ECB mode, the OCBmode, the IPS mode, the VA mode, the FFS mode or the FPA mode.

A composition having a positive dielectric anisotropy is used for an AMdevice having the TN mode. A composition having a negative dielectricanisotropy is used for an AM device having the VA mode. A compositionhaving a positive or negative dielectric anisotropy is used for an AMdevice having the IPS mode or the FFS mode. A composition having apositive or negative dielectric anisotropy is used for an AM devicehaving a polymer sustained alignment (PSA) mode. Compound (1) in thepresent application is disclosed in Patent literature No. 1 describedbelow.

CITATION LIST Patent Literature

Patent literature No. 1: JP S47-027981 A.

SUMMARY OF INVENTION

The invention concerns a liquid crystal composition that has a negativedielectric anisotropy and a nematic phase, and contains at least onecompound selected from the group consisting of compounds represented byformula (1), and a liquid crystal display device including thecomposition:

wherein, in formula (1), R¹ is hydrogen or alkyl having 1 to 15 carbons;R², R³, R⁴ and R⁵ are independently hydrogen or alkyl having 1 to 4carbons; ring A is phenyl or cyclohexyl; and a is 3 or 4.

The invention also concerns use of the liquid crystal composition in aliquid crystal display device having a polymer sustained alignment mode.

DESCRIPTION OF EMBODIMENTS Technical Problem

One of the aims of the invention is to provide a liquid crystalcomposition satisfying at least one of characteristics such as a highmaximum temperature of a nematic phase, a low minimum temperature of thenematic phase, a small viscosity, a suitable optical anisotropy, a largenegative dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat. Another aimis to provide a liquid crystal composition having a suitable balanceregarding at least two of the characteristics. A further aim is toprovide a liquid crystal display device including such a composition. Anadditional aim is an AM device having such characteristics as a shortresponse time, a large voltage holding ratio, a low threshold voltage, alarge contrast ratio and a long service life.

Solution to Problem

The invention concerns a liquid crystal composition that has a negativedielectric anisotropy and a nematic phase, and contains at least onecompound selected from the group consisting of compounds represented byformula (1), and a liquid crystal display device including thecomposition:

wherein, in formula (1), R¹ is hydrogen or alkyl having 1 to 15 carbons;R², R³, R⁴ and R⁵ are independently hydrogen or alkyl having 1 to 4carbons; ring A is phenyl or cyclohexyl; and a is 3 or 4.

The invention also concerns use of the liquid crystal composition in aliquid crystal display device having a polymer sustained alignment mode.

Advantageous Effects of Invention

An advantage of the invention is a liquid crystal composition satisfyingat least one of characteristics such as a high maximum temperature of anematic phase, a low minimum temperature of the nematic phase, a smallviscosity, a suitable optical anisotropy, a large negative dielectricanisotropy, a large specific resistance, a high stability to ultravioletlight and a high stability to heat. Another advantage is a liquidcrystal composition having a suitable balance regarding at least two ofthe characteristics. A further advantage is a liquid crystal displaydevice including such a composition. An additional advantage is an AMdevice having such characteristics as a short response time, a largevoltage holding ratio, a low threshold voltage, a large contrast ratioand a long service life.

Usage of terms herein is as described below. Terms “liquid crystalcomposition” and “liquid crystal display device” may be occasionallyabbreviated as “composition” or “device,” respectively. “Liquid crystaldisplay device” is a generic term for a liquid crystal display panel anda liquid crystal display module. “Liquid crystal compound” is a genericterm for a compound having a liquid crystal phase such as a nematicphase or a smectic phase, or a compound having no liquid crystal phasebut being mixed with the composition for the purpose of adjustingcharacteristics such as a temperature range of the nematic phase,viscosity and dielectric anisotropy. The compound has a six-memberedring such as 1,4-cyclohexylene or 1,4-phenylene, and a rod-likemolecular structure. “Polymerizable compound” is a compound added toform a polymer in the composition. At least one compound selected fromthe group consisting of compounds represented by formula (1) may beoccasionally abbreviated as “compound (1).” “Compound (1)” means onecompound, a mixture of two compounds or a mixture of three or morecompounds represented by formula (1). A same rule applies to any othercompound represented by any other formula.

The liquid crystal composition is prepared by mixing a plurality ofliquid crystal compounds. A ratio (content) of the liquid crystalcompound is expressed in terms of weight percentage (% by weight) basedon the weight of the liquid crystal composition. An additive such as anoptically active compound, an antioxidant, an ultraviolet lightabsorber, a dye, a defoaming agent, a polymerizable compound, apolymerization initiator or a polymerization inhibitor is added to thecomposition if needed. A ratio (an amount of addition) of the additiveis expressed in terms of weight percentage (% by weight) based on theweight of the liquid crystal composition in a manner similar to theratio of the liquid crystal compound. A weight part per million (ppm)may be used in several cases. A ratio of the polymerization initiatorand the polymerization inhibitor is exceptionally expressed based on theweight of the polymerizable compound.

“Higher limit of a temperature range of the nematic phase” may beoccasionally abbreviated as “maximum temperature.” “Lower limit of thetemperature range of the nematic phase” may be occasionally abbreviatedas “minimum temperature.” An expression “having a large specificresistance” means that the composition has a large specific resistanceat room temperature and also at a temperature close to the maximumtemperature of the nematic phase in an initial stage, and that thecomposition has a large specific resistance at room temperature and alsoat a temperature close to the maximum temperature of the nematic phaseeven after the device has been used for a long period of time. Anexpression “having a large voltage holding ratio” means that the devicehas a large voltage holding ratio at room temperature and also at a hightemperature in an initial stage, and that the device has a large voltageholding ratio at room temperature and also at a temperature close to themaximum temperature of the nematic phase even after the device has beenused for a long period of time. An expression “increase dielectricanisotropy” means that a dielectric anisotropy value increasespositively in a composition having a positive dielectric anisotropy, andmeans that the dielectric anisotropy value increases negatively in acomposition having a negative dielectric anisotropy.

An expression “at least one of ‘A’ may be replaced by ‘B’” means thatthe number of ‘A’ is arbitrary. When the number of ‘A’ is one, aposition of ‘A’ is arbitrary, and also when the number of ‘A’ is two ormore, the positions thereof can be selected without a limit. A same rulealso applies to an expression “at least one of ‘A’ is replaced by ‘B’”.

In formula (1) to formula (4), a symbol such as A, B or C surrounded bya hexagonal shape corresponds to ring A, ring B or ring C, respectively.In formula (4), an oblique line crossing the hexagon shape of ring Gmeans that a bonding position on the ring can be arbitrarily selectedfor a P¹-Sp¹ group. A same rule applies to a P²-Sp² group crossing ringI, or the like. A subscript such as f represents the number of groupsbonding with ring G or the like. When f is 2, two P¹-Sp¹ groups exist onring G. Two groups represented by P¹-Sp¹ may be identical or different.A same rule applies also to arbitrary two when f is larger than 2. Asame rule also applies to other groups. The compound represented byformula (1) may be occasionally abbreviated as compound (1). Theabbreviation is also applied to a compound represented by formula (2) orthe like. Compound (1) means one compound or two or more compoundsrepresented by formula (1). A symbol of a terminal group R⁶ is used fora plurality of compounds in chemical formulas of component compounds. Inthe compounds, two groups represented by two arbitrary R⁶ may beidentical or different. In one case, for example, R⁶ of compound (2-1)is ethyl and R⁶ of compound (2-2) is ethyl. In another case, R⁶ ofcompound (2-1) is ethyl and R⁶ of compound (2-2) is propyl. A same ruleapplies to a symbol of any other terminal group or the like. When b is 2in formula (2), two of ring B exist. In the compound, two ringsrepresented by two of ring B may be identical or different. A same ruleapplies to two of arbitrary ring B when b is larger than 2. A same ruleapplies also to a symbol such as Z³ and ring E.

Then, 2-fluoro-1,4-phenylene means two divalent groups described below.In the chemical formulas, fluorine may be leftward (L) or rightward (R).A same rule also applies to a divalent group of an asymmetrical ring,such as tetrahydropyran-2,5-diyl.

The invention includes the items described below.

Item 1. A liquid crystal composition that has a negative dielectricanisotropy and a nematic phase, and contains at least one compoundselected from the group consisting of compounds represented by formula(1):

wherein, in formula (1), R¹ is hydrogen or alkyl having 1 to 15 carbons;R², R³, R⁴ and R⁵ are independently hydrogen or alkyl having 1 to 4carbons; ring A is phenyl or cyclohexyl; and a is 3 or 4.

Item 2. The liquid crystal composition according to item 1, containingat least one compound selected from the group consisting of compoundsrepresented by formula (1-1) and formula (1-2):

Item 3. The liquid crystal composition according to item 1, wherein aratio of the compound represented by formula (1) is in the range of0.005% by weight to 1% by weight based on the weight of the liquidcrystal composition.

Item 4. The liquid crystal composition according to any one of items 1to 3, containing at least one compound selected from the groupconsisting of compounds represented by formula (2) as a first component:

wherein, in formula (2), R⁶ and R⁷ are independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons or alkenyloxy having 2 to 12 carbons; ring B and ring D areindependently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene,1,4-phenylene in which at least one of hydrogen is replaced by fluorineor chlorine, or tetrahydropyran-2,5-diyl; ring C is2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene,2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diylor 7,8-difluorochroman-2,6-diyl; Z¹ and Z² are independently a singlebond, ethylene, methyleneoxy or carbonyloxy; b is 1, 2 or 3 and c is 0or 1; and a sum of b and c is 3 or less.

Item 5. The liquid crystal composition according to any one of items 1to 4, containing at least one compound selected from the groupconsisting of compounds represented by formula (2-1) to formula (2-21)as the first component:

wherein, in formula (2-1) to formula (2-21), R⁶ and R⁷ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons or alkenyloxy having 2 to 12 carbons.

Item 6. The liquid crystal composition according to item 4 or 5, whereina ratio of the first component is in the range of 10% by weight to 90%by weight based on the weight of the liquid crystal composition.

Item 7. The liquid crystal composition according to any one of items 1to 6, containing at least one compound selected from the groupconsisting of compounds represented by formula (3) as a secondcomponent:

wherein, in formula (3), R⁸ and R⁹ are independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons in which at least one ofhydrogen is replaced by fluorine; ring E and ring F are independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene or2,5-difluoro-1,4-phenylene; Z³ is a single bond, ethylene orcarbonyloxy; and d is 1, 2 or 3.

Item 8. The liquid crystal composition according to any one of items 1to 7, containing at least one compound selected from the groupconsisting of compounds represented by formula (3-1) to formula (3-13)as the second component:

wherein, in formula (3-1) to formula (3-13), R⁸ and R⁹ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which atleast one of hydrogen is replaced by fluorine.

Item 9. The liquid crystal composition according to item 7 or 8, whereina ratio of the second component is in the range of 10% by weight to 90%by weight based on the weight of the liquid crystal composition.

Item 10. The liquid crystal composition according to any one of items 1to 9, containing at least one polymerizable compound selected from thegroup consisting of compounds represented by formula (4):

wherein, in formula (4), ring G and ring J are independently cyclohexyl,cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl,1,3-dioxane-2-yl, pyrimidine-2-yl or pyridine-2-yl, and in the rings, atleast one of hydrogen may be replaced by halogen, alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbonsin which at least one of hydrogen is replaced by halogen; ring I is1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene,naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl,naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl,naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl,naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl,pyrimidine-2,5-diyl or pyridine-2,5-diyl, and in the rings, at least oneof hydrogen may be replaced by halogen, alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in whichat least one of hydrogen is replaced by halogen; Z⁴ and Z⁵ areindependently a single bond or alkylene having 1 to 10 carbons, and inthe alkylene, at least one of —CH₂— may be replaced by —O—, —CO—, —COO—or —OCO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH—,—C(CH₃)═CH—, —CH═C(CH₃)— or —C(CH₃)═C(CH₃)—, and in the groups, at leastone of hydrogen may be replaced by fluorine or chlorine; P¹, P² and P³are independently a polymerizable group; Sp¹, Sp² and Sp³ areindependently a single bond or alkylene having 1 to 10 carbons, and inthe alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO—or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or—C≡C—, and in the groups, at least one of hydrogen may be replaced byfluorine or chlorine; e is 0, 1 or 2; f, g and h are independently 0, 1,2, 3 or 4; and a sum of f, g and h is 1 or more.

Item 11. The liquid crystal composition according to item 10, wherein,in formula (4), P¹, P² and P³ are independently a polymerizable groupselected from the group consisting of groups represented by formula(P-1) to formula (P-6):

wherein, in formula (P-1) to formula (P-6), M¹, M² and M³ areindependently hydrogen, fluorine, alkyl having 1 to 5 carbons, or alkylhaving 1 to 5 carbons in which at least one of hydrogen is replaced byhalogen; when all of f pieces of P¹ and h pieces of P³ are a grouprepresented by formula (P-4), in formula (4), at least one of f piecesof Sp¹ and h pieces of Sp³ is alkylene in which at least one of —CH₂— isreplaced by —O—, —COO—, —OCO— or —OCOO—.

Item 12. The liquid crystal composition according to any one of items 1to 11, containing at least one polymerizable compound selected from thegroup consisting of compounds represented by formula (4-1) to formula(4-27):

wherein, in formula (4-1) to formula (4-27), P⁴, P⁵ and P⁶ areindependently a polymerizable group selected from the group consistingof groups represented by formula (P-1) to formula (P-3);

wherein, in formula (P-1) to formula (P-3), M¹, M² and M³ areindependently hydrogen, fluorine, alkyl having 1 to 5 carbons, or alkylhaving 1 to 5 carbons in which at least one of hydrogen is replaced byhalogen; in formula (4-1) to formula (4-27), Sp¹, Sp² and Sp³ areindependently alkylene having 1 to 10 carbons, and in the alkylene, atleast one of —CH₂— may be replaced by —O—, —COO—, —OCO— or —OCOO—, atleast one of —CH₂—CH₂— may be replaced by —CH═CH— or —C≡C—, and in thegroups, at least one of hydrogen may be replaced by fluorine orchlorine.

Item 13. The liquid crystal composition according to item 10, wherein aratio of the compound represented by formula (4) is in the range of0.03% by weight to 10% by weight based on the weight of the liquidcrystal composition.

Item 14. A liquid crystal display device, including the liquid crystalcomposition according to any one of items 1 to 13.

Item 15. The liquid crystal display device according to item 14, whereinan operating mode in the liquid crystal display device includes an IPSmode, a VA mode, an FFS mode or an FPA mode, and a driving mode in theliquid crystal display device includes an active matrix mode.

Item 16. A liquid crystal display device having a polymer sustainedalignment mode, including the liquid crystal composition according toany one of items 10 to 13, wherein the polymerizable compound in theliquid crystal composition is polymerized.

Item 17. Use of the liquid crystal composition according to any one ofitems 1 to 13 in a liquid crystal display device.

Item 18. Use of the liquid crystal composition according to any one ofitems 10 to 13 in a liquid crystal display device having a polymersustained alignment mode.

The invention further also includes the following items: (a) thecomposition further containing at least one additive such as anoptically active compound, an antioxidant, an ultraviolet lightabsorber, a dye, a defoaming agent, a polymerizable compound, apolymerization initiator and a polymerization inhibitor; (b) an AMdevice including the composition; (c) an AM device having a polymersustained alignment (PSA) mode, which includes the composition andfurther includes a polymerizable compound; (d) an AM device having apolymer sustained alignment (PSA) mode, which includes the composition,wherein the polymerizable compound in the composition is polymerized;(e) a device including the composition, and having a PC, TN, STN, ECB,OCB, IPS, VA, FFS or FPA mode; (f) a transmissive device including thecomposition; (g) use of the composition as the composition having thenematic phase; and (h) use as an optically active composition by addingthe optically active compound to the composition.

The composition of the invention will be described in the followingorder. First, a constitution of the component compounds in thecomposition will be described. Second, main characteristics of thecomponent compounds and main effects of the compounds on the compositionwill be described. Third, a combination of components in thecomposition, a preferred ratio of the component compounds and the basisthereof will be described. Fourth, a preferred embodiment of thecomponent compounds will be described. Fifth, preferred componentcompounds are shown. Sixth, an additive that may be added to thecomposition will be described. Seventh, methods for synthesizing thecomponent compounds will be described. Last, an application of thecomposition will be described.

First, the constitution of the component compounds in the compositionwill be described. The composition of the invention is classified intocomposition A and composition B. Composition A may further contain anyother liquid crystal compound, an additive or the like in addition tothe liquid crystal compound selected from compound (2) and compound (3).“Any other liquid crystal compound” means a liquid crystal compounddifferent from compound (2) and compound (3). Such a compound is mixedwith the composition for the purpose of further adjusting thecharacteristics. The additive includes the optically active compound,the antioxidant, the ultraviolet light absorber, the dye, theantifoaming agent, the polymerizable compound, the polymerizationinitiator and the polymerization inhibitor.

Composition B consists essentially of the liquid crystal compoundselected from compound (2) and compound (3). A term “essentially” meansthat the composition may contain the additive, but does not contain anyother liquid crystal compound. An example of composition B is acomposition containing compound (1), compound (2) and compound (3) as anessential component. Composition B has a smaller number of componentsthan composition A has. Composition B is preferred to composition A inview of cost reduction. Composition A is preferred to composition B inview of possibility of further adjusting the characteristics by mixingany other liquid crystal compound.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the characteristics of the composition willbe described. The main characteristics of the component compounds aresummarized in Table 2 on the basis of advantageous effects of theinvention. In Table 2, a symbol L stands for “large” or “high,” a symbolM stands for “medium,” and a symbol S stands for “small” or “low.” Thesymbols L, M and S represent a classification based on a qualitativecomparison among the component compounds, and 0 (zero) means that avalue is zero or nearly zero.

TABLE 2 Characteristics of Compounds Compounds Compound (2) Compound (3)Maximum temperature S to M S to L Viscosity L S to M Optical anisotropyM to L S to L Dielectric anisotropy L¹⁾ 0 Specific resistance L L ¹⁾Avalue of dielectric anisotropy is negative, and the symbol showsmagnitude of an absolute value.

Upon mixing the component compounds with the composition, the maineffects of the component compounds on the characteristics of thecomposition are as described below. Compound (1) contributes to a highstability to heat or ultraviolet light. Compound (1) produces nodifference to the characteristics of the maximum temperature, theoptical anisotropy and the dielectric anisotropy. Compound (2) being thefirst component increases the dielectric anisotropy, and decreases theminimum temperature. Compound (3) being the second component decreasesthe viscosity or increases the maximum temperature. Compound (4) yieldsa polymer by polymerization, and the polymer shortens the response timein the device, and improves image persistence.

Third, the combination of components in the composition, the preferredratio of the component compounds and the basis thereof will bedescribed. The preferred combination of components in the compositionincludes a combination of compound (1) and the first component, acombination of compound (1) and the second component, a combination ofcompound (1), the first component and the second component, acombination of compound (1), the first component and compound (4), acombination of compound (1), the second component and compound (4), or acombination of compound (1), the first component, the second componentand compound (4). A further preferred combination is a combination ofcompound (1), the first component and the second component.

The preferred addition ratio of compound (1) is approximately 0.005% byweight or more, based on the weight of the liquid crystal composition,for contributing to the high stability to heat or ultraviolet light, andapproximately 1% by eight or less for decreasing the minimumtemperature. A further preferred ratio is in the range of approximately0.01% by weight to approximately 0.5% by weight based thereon. Aparticularly preferred ratio of addition is in the range ofapproximately 0.03% by weight to approximately 0.3% by weight, basedthereon.

A preferred ratio of the first component is approximately 10% by weightor more for increasing the dielectric anisotropy, and approximately 90%by weight or less for decreasing the minimum temperature, based on theweight of the liquid crystal composition. A further preferred ratio isin the range of approximately 20% by weight to approximately 80% byweight based thereon. A particularly preferred ratio is in the range ofapproximately 30% by weight to approximately 70% by weight basedthereon.

A preferred ratio of the second component is approximately 10% by weightor more for increasing the maximum temperature or decreasing theviscosity, and approximately 90% or less for increasing the dielectricanisotropy, based on the weight of the liquid crystal composition. Afurther preferred ratio is in the range of approximately 20% by weightto approximately 80% by weight based thereon. A particularly preferredratio is in the range of approximately 30% by weight to approximately70% by weight based thereon.

Compound (4) is added to the composition for allowing the composition toadapt to the liquid crystal display device having a polymer sustainedalignment mode. A preferred ratio of addition of the additive isapproximately 0.03% by weight or more for aligning liquid crystalmolecules and approximately 10% by weight or less for preventing poordisplay on the device, based on the weight of the liquid crystalcomposition. A further preferred ratio of addition is in the range ofapproximately 0.1% by weight to approximately 2% by weight basedthereon. A particularly preferred ratio of addition is approximately0.2% by weight to approximately 1.0% by weight based thereon.

Fourth, the preferred embodiment of the component compounds will bedescribed. In formula (1), R¹ is hydrogen or alkyl having 1 to 15carbons. Preferred R¹ is hydrogen or methyl. R², R³, R⁴ and R⁵ areindependently hydrogen or alkyl having 1 to 4 carbons. Preferred R², R³,R⁴ or R⁵ is hydrogen or methyl.

Ring A is phenyl or cyclohexyl. Preferred ring A is phenyl.

Then, a is 3 or 4. Preferred a is 4.

In formula (2) and formula (3), R⁶ and R⁷ are independently alkyl having1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons or alkenyloxy having 2 to 12 carbons. Preferred R⁶ or R⁷ isalkyl having 1 to 12 carbons for increasing the stability, and alkoxyhaving 1 to 12 carbons for increasing the dielectric anisotropy. R⁸ andR⁹ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which at least one of hydrogen is replaced by fluorine.Preferred R⁸ or R⁹ is alkenyl having 2 to 12 carbons for decreasing theviscosity, and alkyl having 1 to 12 carbons for increasing thestability.

Preferred alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. Further preferred alkyl is ethyl, propyl, butyl, pentyl orheptyl for decreasing the viscosity.

Preferred alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. Further preferred alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Preferred alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. Furtherpreferred alkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl fordecreasing the viscosity. A preferred configuration of —CH═CH— in thealkenyl depends on a position of a double bond. Trans is preferred inthe alkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl,3-pentenyl and 3-hexenyl for decreasing the viscosity, for instance. Cisis preferred in the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl.In the alkenyl, straight-chain alkenyl is preferred to branched-chainalkenyl.

Preferred alkenyloxy is vinyloxy, allyloxy, 3-butenyloxy, 3-pentenyloxyor 4-pentenyloxy. A further preferred alkenyloxy is allyloxy or3-butenyloxy for decreasing the viscosity.

Preferred examples of alkenyl in which at least one of hydrogen isreplaced by fluorine include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl or6,6-difluoro-5-hexenyl. A further preferred example is 2,2-difluorovinylor 4,4-difluoro-3-butenyl for decreasing the viscosity.

Ring B and ring D are independently 1,4-cyclohexylene,1,4-cyclohexenylene, 1,4-phenylene, 1,4-phenylene in which at least oneof hydrogen is replaced by fluorine or chlorine, ortetrahydropyran-2,5-diyl. Preferred examples of “1,4-phenylene in whichat least one of hydrogen is replaced by fluorine or chlorine” include2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene or2-chloro-3-fluoro-1,4-phenylene. Preferred ring B or ring D is1,4-cyclohexylene for decreasing the viscosity, tetrahydropyran-2,5-diylfor increasing the dielectric anisotropy, and 1,4-phenylene forincreasing the optical anisotropy. With regard to a configuration of1,4-cyclohexylene, trans is preferred to cis for increasing the maximumtemperature. Tetrahydropyran-2,5-diyl includes:

and preferably

Ring C is 2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene,2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diylor 7,8-difluorochroman-2,6-diyl. Preferred ring C is2,3-difluoro-1,4-phenylene for decreasing the viscosity,2-chloro-3-fluoro-1,4-phenylene for decreasing the optical anisotropy,and 7,8-difluorochroman-2,6-diyl for increasing the dielectricanisotropy.

Ring E and Ring F are independently 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene. Preferred ring Eor ring F is 1,4-cyclohexylene for decreasing the viscosity orincreasing the maximum temperature, and 1,4-phenylene for decreasing theminimum temperature.

Z¹ and Z² are independently a single bond, ethylene, methyleneoxy orcarbonyloxy. Preferred Z¹ or Z² is a single bond for decreasing theviscosity, ethylene for decreasing the minimum temperature, andmethyleneoxy for increasing the dielectric anisotropy. Z³ is a singlebond, ethylene or carbonyloxy. Preferred Z³ is a single bond fordecreasing the viscosity.

Then, b is 1, 2, or 3. Preferred b is 1 for decreasing the viscosity,and 2 or 3 for increasing the maximum temperature. Further, c is 0 or 1.Preferred c is 0 for decreasing the viscosity, and 1 for decreasing theminimum temperature. Then, d is 1, 2 or 3. Preferred d is 1 fordecreasing the viscosity, and 2 or 3 for increasing the maximumtemperature.

In formula (4), P¹, P² and P³ are independently a polymerizable group.Preferred P¹, P² or P³ is a polymerizable group selected from the groupconsisting of groups represented by formula (P-1) to formula (P-6).Further preferred P¹, P² or P³ is group (P-1) or group (P-2).Particularly preferred group (P-1) is —OCO—CH═CH₂ or —OCO—C(CH₃)═CH₂. Awavy line in group (P-1) to group (P-6) represents a part to be bonded.

In group (P-1) to group (P-6), M¹, M² and M³ are independently hydrogen,fluorine, alkyl having 1 to 5 carbons, or alkyl having 1 to 5 carbons inwhich at least one of hydrogen is replaced by halogen. Preferred M¹, M²or M³ is hydrogen or methyl for increasing reactivity. Further preferredM¹ is methyl and further preferred M² or M³ is hydrogen. When at leasttwo of f pieces of P¹, e×g pieces of P² and h pieces of P³ are group(P-1), two of arbitrary M¹, M² or M³ of P¹, P² and P³ may be identicalor different. A same rule applies to group (P-2) or group (P-3).

When all of f pieces of P¹ and h pieces of P³ are group (P-4), in atleast one of f pieces of Sp¹ and g pieces of Sp³, at least one of —CH₂—is alkylene replaced by —O—, —COO—, —OCO— or —OCOO—. More specifically,a case where all of f pieces of P¹ and h pieces of P³ are alkenyl suchas 1-propenyl is excluded.

In formula (4-1) to formula (4-27), P⁴, P⁵ and P⁶ are independently agroup represented by formula (P-1) to formula (P-3). Preferred P⁴, P⁵ orP⁶ is group (P-1) or group (P-2). Further preferred group (P-1) is—OCO—CH═CH₂ or —OCO—O(CH₃)═CH₂. A wavy line in group (P-1) to group(P-6) represents a part to be bonded.

When at least two of one or two of P⁴, one or two of P⁵ and one or twoof P⁶ are group (P-1), two of arbitrary M¹, M² or M³ of P⁴, P⁵ and P⁶may be identical or different. A same rule applies also to a case whereat least two thereof is group (P-2) or group (P-3).

In formula (4), Sp¹, Sp² and Sp³ are independently a single bond oralkylene having 1 to 10 carbons, and in the alkylene, at least one of—CH₂— may be replaced by —O—, —COO—, —OCO— or —OCOO—, at least one of—CH₂—CH₂— may be replaced by —CH═CH— or —C≡C—, and in the groups, atleast one of hydrogen may be replaced by fluorine or chlorine. PreferredSp¹, Sp² or Sp³ is a single bond.

Ring G and ring J are independently cyclohexyl, cyclohexenyl, phenyl,1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl, 1,3-dioxane-2-yl,pyrimidine-2-yl, or pyridine-2-yl, and in the rings, at least one ofhydrogen may be replaced by halogen, alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in whichat least one of hydrogen is replaced by halogen. Preferred ring G andring J are phenyl. Ring I is 1,4-cyclohexylene, 1,4-cyclohexenylene,1,4-phenylene, naphthalene-1,2-diyl, naphthalene-1,3-diyl,naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,6-diyl,naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl,naphthalene-2,6-diyl, naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl,1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl, and inthe rings, at least one of hydrogen may be replaced by halogen, alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1to 12 carbons in which at least one of hydrogen is replaced by halogen.Preferred ring I is 1,4-phenylene or 2-fluoro-1,4-phenylene.

Z⁴ and Z⁵ are independently a single bond or alkylene having 1 to 10carbons, and in the alkylene, at least one of —CH₂— may be replaced by—O—, —CO—, —COO— or —OCO—, at least one of —CH₂—CH₂— may be replaced by—CH═CH—, —C(CH₃)═CH—, —CH═C(CH₃)— or —C(CH₃)═C(CH₃)—, and in the groups,at least one of hydrogen may be replaced by fluorine or chlorine.Preferred Z⁴ or Z⁵ is a single bond, —CH₂CH₂—, —CH₂O—, —OCH₂—, —COO— or—OCO—. Further preferred Z⁴ or Z⁵ is a single bond.

Then, e is 0, 1, or 2. Preferred e is 0 or 1. Further, f, g and h areindependently 0, 1, 2, 3 or 4, and a sum of f, g and h is 1 or more.Preferred f, g or h is 1 or 2.

Fifth, the preferred component compounds are shown. Preferred compound(1) includes compound (1-1) and compound (1-2) as described in item 2.Further preferred compound (1) includes compound (1-1).

Preferred compound (2) includes compound (2-1) to compound (2-21) asdescribed in item 5. In the compounds, at least one of the firstcomponents preferably includes compound (2-1), compound (2-4), compound(2-5), compound (2-7), compound (2-10) or compound (2-15). At least twoof the first components preferably includes a combination of compound(2-1) and compound (2-7), a combination of compound (2-1) and compound(2-15), a combination of compound (2-4) and compound (2-7), acombination of compound (2-4) and compound (2-15), or a combination ofcompound (2-5) and compound (2-10).

Preferred compound (3) includes compound (3-1) to compound (3-13) asdescribed in item 8. In the compounds, at least one of the secondcomponents includes compound (3-1), compound (3-3), compound (3-5),compound (3-6), compound (3-7) or compound (3-8). At least two of thesecond components preferably includes a combination of compound (3-1)and compound (3-3), a combination of compound (3-1) and compound (3-5),or a combination of compound (3-1) and compound (3-6).

Preferred compound (4) includes compound (4-1) to compound (4-27) asdescribed in item 12. In the compounds, at least one of the additivecomponents preferably includes compound (4-1), compound (4-2), compound(4-24), compound (4-25), compound (4-26) or compound (4-27). At leasttwo of the additive components preferably includes a combination ofcompound (4-1) and compound (4-2), a combination of compound (4-1) andcompound (4-18), a combination of compound (4-2) and compound (4-24), acombination of compound (4-2) and compound (4-25), a combination ofcompound (4-2) and compound (4-26), a combination of compound (4-25) andcompound (4-26), or a combination of compound (4-18) and compound(4-24). In group (P-1) to group (P-3), preferred M¹, M² or M³ ishydrogen or methyl. Preferred Sp¹, Sp² or Sp³ is a single bond,—CH₂CH₂—, —CH₂O—, —OCH₂—, —COO—, —OCO—, —CO—CH═CH— or —CH═CH—CO—.

Sixth, the additive that may be added to the composition will bedescribed. Such an additive includes the optically active compound, theantioxidant, the ultraviolet light absorber, the dye, the antifoamingagent, the polymerizable compound, the polymerization initiator and thepolymerization inhibitor. The optically active compound is added to thecomposition for the purpose of inducing a helical structure in liquidcrystals to give a twist angle. Examples of such a compound includecompound (5-1) to compound (5-5). A preferred ratio of the opticallyactive compound is approximately 5% by weight or less. A furtherpreferred ratio is in the range of approximately 0.01% by weight toapproximately 2% by weight.

The antioxidant is added to the composition for the purpose ofpreventing a decrease in specific resistance caused by heating in air,or maintaining a large voltage holding ratio at room temperature andalso at a temperature close to the maximum temperature of the nematicphase after the device has been used for a long period of time.Preferred examples of the antioxidant include compound (6) where n is aninteger from 1 to 9.

In compound (6), preferred n is 1, 3, 5, 7 or 9. Further preferred n is7. Compound (6) where n is 7 is effective in maintaining a large voltageholding ratio at room temperature and also at a temperature close to themaximum temperature after the device has been used for a long period oftime because such compound (6) has a small volatility. A preferred ratioof the antioxidant is approximately 50 ppm or more for achieving theeffect thereof, and approximately 600 ppm or less for avoiding adecrease in the maximum temperature or avoiding an increase in theminimum temperature. A further preferred ratio is in the range ofapproximately 100 ppm to approximately 300 ppm.

Preferred examples of the ultraviolet light absorber include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also preferred. A preferred ratio of the ultraviolet light absorberor the stabilizer is approximately 50 ppm or more for achieving theeffect thereof, and approximately 10,000 ppm or less for avoiding adecrease in the maximum temperature or avoiding an increase in theminimum temperature. A further preferred ratio is in the range ofapproximately 100 ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is added tothe composition to be adapted for a device having a guest host (GH)mode. A preferred ratio of the dye is in the range of approximately0.01% by weight to approximately 10% by weight. The antifoaming agentsuch as dimethyl silicone oil or methyl phenyl silicone oil is added tothe composition for preventing foam formation. A preferred ratio of theantifoaming agent is approximately 1 ppm or more for achieving theeffect thereof, and approximately 1,000 ppm or less for avoiding a poordisplay. A further preferred ratio is in the range of approximately 1ppm to approximately 500 ppm.

The polymerizable compound is used to be adapted for a device having thepolymer sustained alignment (PSA) mode. Compound (4) is suitable for theabove purpose. A polymerizable compound different from compound (4) maybe added to the composition together with compound (4). Preferredexamples of such a polymerizable compound include a compound such as anacrylate, a methacrylate, a vinyl compound, a vinyloxy compound, apropenyl ether, an epoxy compound (oxirane, oxetane) and vinyl ketone.Further preferred examples include a derivative of acrylate ormethacrylate. A preferred ratio of compound (4) is approximately 10% byweight or more based on the total weight of the polymerizable compound.A further preferred ratio is approximately 50% by weight or more basedthereon. A particularly preferred ratio is approximately 80% by weightor more based thereon. A most preferred ratio is approximately 100% byweight based thereon.

The polymerizable compound such as compound (4) polymerizes byirradiation with ultraviolet light. The compound may be polymerized alsoin the presence of a suitable initiator such as a photopolymerizationinitiator. Suitable conditions for polymerization, suitable types of theinitiator and suitable amounts thereof are known to those skilled in theart and are described in literature. For example, Irgacure 651(registered trademark; BASF), Irgacure 184 (registered trademark; BASF)or Darocur 1173 (registered trademark; BASF), each being aphotopolymerization initiator, is suitable for radical polymerization. Apreferred ratio of the photopolymerization initiator is in the range ofapproximately 0.1% by weight to approximately 5% by weight based on thetotal weight of the polymerizable compound. A further preferred ratio isin the range of approximately 1% by weight to approximately 3% by weightbased thereon.

When the polymerizable compound such as compound (4) is stored, thepolymerization inhibitor may be added for preventing polymerization. Thepolymerizable compound is ordinarily added to the composition withoutremoving the polymerization inhibitor. Examples of the polymerizationinhibitor include hydroquinone and a hydroquinone derivative such asmethylhydroquinone, 4-tert-butylcatechol, 4-methoxy phenol andphenothiazine.

Seventh, the methods for synthesizing the component compounds will bedescribed. The compounds can be prepared according to known methods.Examples of synthetic methods will be presented. Compound (1-1) isprepared by the method described in JP S47-027981 A. Compound (2-1) isprepared by the method described in JP 2000-053602 A. Compound (3-1) isprepared by the method described in JP S59-176221 A. Compound (3-13) isprepared by the method described in JP H2-237949 A. Compound (4-18) isprepared by the method described in JP H7-101900 A. A compoundrepresented by formula (6) where n is 1 is available from Sigma-AldrichCorporation. Compound (6) where n is 7 and so forth are preparedaccording to the method described in U.S. Pat. No. 3,660,505 B.

Any compounds whose synthetic methods are not described above can beprepared according to the methods described in books such as OrganicSyntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley &Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press) and NewExperimental Chemistry Course (Shin Jikken Kagaku Koza in Japanese)(Maruzen Co., Ltd.). The composition is prepared according to publiclyknown methods using the thus obtained compounds. For example, thecomponent compounds are mixed and dissolved in each other by heating.

Last, the application of the composition will be described. Thecomposition mainly has a minimum temperature of approximately −10° C. orlower, a maximum temperature of approximately 70° C. or higher, and anoptical anisotropy in the range of approximately 0.07 to approximately0.20. The device including the composition has a large voltage holdingratio. The composition is suitable for use in the AM device. Thecomposition is particularly suitable for use in a transmissive AMdevice. The composition having an optical anisotropy in the range ofapproximately 0.08 to approximately 0.25, and also the compositionhaving an optical anisotropy in the range of approximately 0.10 toapproximately 0.30 may be prepared by controlling the ratio of thecomponent compounds or by mixing with any other liquid crystal compound.The composition can be used as the composition having the nematic phaseand as the optically active composition by adding the optically activecompound.

The composition can be used for the AM device. The composition can alsobe used for a PM device. The composition can be used for an AM deviceand a PM device having a mode such as PC, TN, STN, ECB, OCB, IPS, FFS,VA or FPA. Use for an AM device having the TN, OCB, IPS or FFS mode isparticularly preferred. In an AM device having the IPS mode or FFS mode,alignment of the liquid crystal molecules when no voltage is applied maybe parallel or perpendicular to a glass substrate. The devices may be ofa reflective type, a transmissive type or a transflective type. Use forthe transmissive device is preferred. The composition can also be usedfor an amorphous silicon-TFT device or a polycrystal silicon-TFT device.The composition can also be used for a nematic curvilinear aligned phase(NCAP) device prepared by microencapsulating the composition, and for apolymer dispersed (PD) device in which a three-dimensional networkpolymer is formed in the composition.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention and specificexamples provided herein without departing from the spirit or scope ofthe invention. Thus, it is intended that the invention covers themodifications and variations of this invention that come within thescope of any claims and their equivalents.

The following examples are for illustrative purposes only and are notintended, nor should they be interpreted to, limit the scope of theinvention.

EXAMPLES

The invention will be described in greater detail by way of Examples.The invention is not restricted by the Examples. The invention includesa mixture of a composition in Example 1 and a composition in Example 2.The invention also includes a mixture obtained by mixing at least two ofcompositions in Composition Examples. A prepared compound was identifiedby a method such as NMR analysis. Characteristics of a compound and thecomposition were measured by methods as described below.

NMR analysis: For measurement, DRX-500 made by Bruker BioSpinCorporation was used. In ¹H-NMR measurement, a sample was dissolved in adeuterated solvent such as CDCl₃, and measurement was carried out underconditions of room temperature, 500 MHz and 16 times of accumulation.Tetramethylsilane was used as an internal standard. In ¹⁹F-NMRmeasurement, measurement was carried out under conditions of 24 times ofaccumulation using CFCl₃ as an internal standard. In the explanation ofnuclear magnetic resonance spectra, s, d, t, q, quin, sex, m stand for a4 singlet, a doublet, a triplet, a quartet, a quintet, a sextet and amultiplet, respectively, and br being broad.

Gas chromatographic analysis: GC-14B Gas Chromatograph made by ShimadzuCorporation was used for measurement. A carrier gas was helium (2mL/min). A sample injector and a detector (FID) were set to 280° C. and300° C., respectively. A capillary column DB-1 (length 30 m, bore 0.32mm, film thickness 0.25 μm; dimethylpolysiloxane as a stationary phase,non-polar) made by Agilent Technologies, Inc. was used for separation ofcomponent compounds. After the column was kept at 200° C. for 2 minutes,the column was heated to 280° C. at a rate of 5° C. per minute. A samplewas prepared in an acetone solution (0.1% by weight), and then 1microliter of the solution was injected into the sample injector. Arecorder was C-R5A Chromatopac made by Shimadzu Corporation or anequivalent thereof. The resulting chromatogram showed a retention timeof a peak and a peak area corresponding to each of the componentcompounds.

As a solvent for diluting the sample, chloroform, hexane and so forthmay also be used. The following capillary columns may also be used forseparating the component compounds: HP-1 (length 30 m, bore 0.32 mm,film thickness 0.25 μm) made by Agilent Technologies, Inc., Rtx-1(length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by RestekCorporation and BP-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm)made by SGE International Pty. Ltd. A capillary column CBP1-M50-025(length 50 m, bore 0.25 mm, film thickness 0.25 μm) made by ShimadzuCorporation may also be used for the purpose of avoiding an overlap ofpeaks of the compounds.

A ratio of liquid crystal compounds contained in the composition may becalculated by the method as described below. A mixture of liquid crystalcompounds is detected with a gas chromatograph (FID). A ratio of peakareas in a gas chromatogram corresponds to a ratio (weight ratio) of theliquid crystal compounds. When the capillary columns described abovewere used, a correction coefficient of each of the liquid crystalcompounds may be regarded as 1 (one). Accordingly, a ratio (% by weight)of the liquid crystal compounds can be calculated from the ratio of thepeak areas.

Sample for measurement: When characteristics of a composition aremeasured, the composition was used as a sample as was. Whencharacteristics of a compound were measured, a sample for measurementwas prepared by mixing the compound (15% by weight) with a base liquidcrystal (85% by weight). Values of characteristics of the compound werecalculated using values obtained by measurement, according to anextrapolation method: (extrapolated value)={(measured value of asample)−0.85×(measured value of base liquid crystal)}/0.15. When asmectic phase (or crystals) precipitated at the ratio thereof at 25° C.,a ratio of the compound to the base liquid crystal was changed step bystep in the order of (10% by weight:90% by weight), (5% by weight:95% byweight) and (1% by weight:99% by weight). Values of maximum temperature,optical anisotropy, viscosity and dielectric anisotropy with regard tothe compound were determined according to the extrapolation method.

The base liquid crystal as described below was used. Ratios of thecomponent compounds are shown in terms of percent by weight.

17.2%

27.6%

20.7%

20.7%

13.8%

Measurement method: Measurement of characteristics was carried out bymethods described below. Most of the measurement methods were applied asdescribed in the Standard of the Japan Electronics and InformationTechnology Industries Association (hereinafter abbreviated as JEITA)(JEITA EIAJ ED-2521B) discussed and established by JEITA, or modifiedthereon. No thin film transistor (TFT) was attached to a TN device usedfor measurement.

(1) Maximum temperature of a nematic phase (NI; ° C.): A sample wasplaced on a hot plate in a melting point apparatus equipped with apolarizing microscope and was heated at a rate of 1° C. per minute.Temperature when part of the sample began to change from a nematic phaseto an isotropic liquid was measured. A higher limit of a temperaturerange of the nematic phase may be abbreviated as “maximum temperature”.

(2) Minimum temperature of a nematic phase (T_(c); ° C.): Samples eachhaving a nematic phase were put in glass vials and kept in freezers attemperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10days, and then liquid crystal phases were observed. For example, whenthe sample maintained the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., T_(c) was expressed asT_(c)<−20° C. A lower limit of the temperature range of the nematicphase may be abbreviated as “minimum temperature”.

(3) Viscosity (bulk viscosity; γ₁; measured at 20° C.; mPa·s): Acone-plate type (E-type) rotational viscometer made by Tokyo Keiki Co.,Ltd. was used for measurement.

(4) Viscosity (rotational viscosity; γ1; measured at 25° C.; mPa·s):Measurement was carried out according to the method described in M. Imaiet al., Molecular Crystals and Liquid Crystals, Vol. 259, p. 37 (1995).A sample was put in a VA device in which a distance (cell gap) betweentwo glass substrates was 20 micrometers. Voltage was applied stepwise tothe device in the range of 39 V to 50 V at an increment of 1 V. After aperiod of 0.2 second with no voltage application, voltage was appliedrepeatedly under the conditions of only one rectangular wave(rectangular pulse; 0.2 second) and no voltage application (2 seconds).A peak current and a peak time of a transient current generated by theapplied voltage were measured. A value of rotational viscosity wasobtained from the measured values and a calculation equation (8) on page40 of the paper presented by M. Imai et al. Dielectric anisotropyrequired for the calculation was measured according to measurement (6)described below.

(5) Optical anisotropy (refractive index anisotropy; Δn; measured at 25°C.): Measurement was carried out by an Abbe refractometer with apolarizing plate mounted on an ocular, using light at a wavelength of589 nanometers. A surface of a main prism was rubbed in one direction,and then a sample was added dropwise onto the main prism. A refractiveindex (n∥) was measured when the direction of polarized light wasparallel to the direction of rubbing. A refractive index (n⊥) wasmeasured when the direction of polarized light was perpendicular to thedirection of rubbing. A value of optical anisotropy was calculated froman equation: Δn=n∥−n⊥.

(6) Dielectric anisotropy (Δ∈; measured at 25° C.): A value ofdielectric anisotropy was calculated from an equation: Δ∈=∈∥−∈⊥. Adielectric constant (∈∥ and ∈⊥) was measured as described below.

(1) Measurement of dielectric constant (E∥): An ethanol (20 mL) solutionof octadecyl triethoxysilane (0.16 mL) was applied to a well-cleanedglass substrate. After rotating the glass substrate with a spinner, theglass substrate was heated at 150° C. for 1 hour. A sample was put in aVA device in which a distance (cell gap) between two glass substrateswas 4 micrometers, and the device was sealed with an ultraviolet-curableadhesive. Sine waves (0.5 V, 1 kHz) were applied to the device, andafter 2 seconds, a dielectric constant (∈∥) in the major axis directionof liquid crystal molecules was measured.

(2) Measurement of dielectric constant (∈‥): A polyimide solution wasapplied to a well-cleaned glass substrate. After calcining the glasssubstrate, rubbing treatment was applied to the alignment film obtained.A sample was put in a TN device in which a distance (cell gap) betweentwo glass substrates was 9 micrometers and a twist angle was 80 degrees.Sine waves (0.5 V, 1 kHz) were applied to the device, and after 2seconds, a dielectric constant (∈⊥) in the minor axis direction of theliquid crystal molecules was measured.

(7) Threshold voltage (Vth; measured at 25° C.; V): An LCD-5100luminance meter made by Otsuka Electronics Co., Ltd. was used formeasurement. A light source was a halogen lamp. A sample was put in a VAdevice of a normally black mode, in which a distance (cell gap) betweentwo glass substrates was 4 micrometers and a rubbing direction wasanti-parallel, and the device was sealed with an ultraviolet-curableadhesive. A voltage (60 Hz, rectangular waves) to be applied to thedevice was increased stepwise from 0 V to 20 V at an increment of 0.02V. On the occasion, the device was irradiated with light from adirection perpendicular to the device, and the amount of lighttransmitted through the device was measured. A voltage-transmittancecurve was prepared, in which the maximum amount of light corresponds to100% transmittance and the minimum amount of light corresponds to 0%transmittance. A threshold voltage was expressed in terms of a voltageat 10% transmittance.

(8) Voltage holding ratio (VHR-a; measured at 25° C.; %): A PVA deviceused for measurement had a polyimide alignment film, and a distance(cell gap) between two glass substrates was 3.5 micrometers. A samplewas put in the device, and then the device was sealed with anultraviolet-curable adhesive. A pulse voltage (60 microseconds at 1 V)was applied to the PVA device and the device was charged. A decayingvoltage was measured for 166.7 milliseconds with a high-speed voltmeter,and area A between a voltage curve and a horizontal axis in a unit cyclewas determined. Area B was an area without decay. A voltage holdingratio was expressed in terms of percentage of area A to area B.

(9) Voltage holding ratio (VHR-b; measured at 60° C.; %): A voltageholding ratio was measured in a manner similar to the procedures asdescribed above except that measurement was carried out at 60° C. inplace of 25° C. A value obtained was expressed in terms of VHR-b.

(10) Voltage holding ratio (VHR-c; measured at 60° C.; %): Stability toultraviolet light was evaluated by measuring a voltage holding ratioafter a device was irradiated with ultraviolet light. A PVA device usedfor measurement had a polyimide alignment film, and a cell gap was 3.5micrometers. A sample was injected into the device, and then the devicewas irradiated with light for 167 minutes. A light source was a blacklight (peak wavelength: 369 nm), and a distance between the device andthe light source was 5 mm. In VHR-c measurement, a decaying voltage wasmeasured for 166.7 milliseconds. A composition having a large VHR-c hasa large stability to ultraviolet light.

(11) Voltage holding ratio (VHR-d; measured at 25° C.; %): A PVA deviceinto which a sample was injected was heated in a constant-temperaturebath at 150° C. for 2 hours, and then stability to heat was evaluated bymeasuring a voltage holding ratio. In VHR-d measurement, a decayingvoltage was measured for 166.7 milliseconds. A composition having alarge VHR-4 has a large stability to heat.

(12) Response time (τ; measured at 25° C.; ms): An LCD-5100 luminancemeter made by Otsuka Electronics Co., Ltd. was used for measurement. Alight source was a halogen lamp. A low-pass filter was set at 5 kHz. Asample was put in a VA device of a normally black mode, in which adistance (cell gap) between two glass substrates was 4 micrometers and arubbing direction was anti-parallel, and the device was sealed with anultraviolet-curable adhesive. Rectangular waves (60 Hz, 10 V, 0.5second) were applied to the device. On the occasion, the device wasirradiated with light from a direction perpendicular to the device, andthe amount of light transmitted through the device was measured. Themaximum amount of light was regarded as correspondence to 100%transmittance, and the minimum amount of light as correspondence to 0%transmittance. A response time was expressed in terms of time requiredfor a change from 90% transmittance to 10% transmittance (fall time;millisecond).

(13) Specific resistance (p; measured at 25° C.; 0 cm): Into a vesselequipped with electrodes, 1.0 milliliter of a sample was injected. A DCvoltage (10 V) was applied to the vessel, and a DC current after 10seconds was measured. A specific resistance was calculated from thefollowing equation: (specific resistance)−{(voltage)×(electric capacityof a vessel)}/{(direct current)×(dielectric constant of vacuum)}.

The compounds in Examples and Comparative Example were expressed usingsymbols according to definitions in Table 3 below. In Table 3, aconfiguration of 1,4-cyclohexylene is trans. A parenthesized number nextto a symbolized compound corresponds to the number of the compound. Asymbol (−) means any other liquid crystal compound. A ratio (percentage)of a liquid crystal compound is expressed in terms of weight percentage(% by weight) based on the weight of the liquid crystal composition.Values of characteristics of the composition were summarized in the lastpart.

TABLE 3 Method for Description of Compounds using Symbols R—(A₁)—Z₁—. ..—Z_(n)—(A_(n))—R′ 1) Left-terminal Group R— Symbol F—C_(n)H_(2n)— Fn-C_(n)H_(2n+1)— n- C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn-CH₂═CH— V— C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)—CH═CH—C_(n)C_(2n)— mVn- CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn- CH₂═CH—COO— AC— CH₂═C(CH₃)—COO— MAC— 2) Right-terminal Group —R′Symbol —C_(n)H_(2n+1) -n —OC_(n)H_(2n+1) —On —CH═CH₂ —V—CH═CH—C_(n)H_(2n+1) —Vn —C_(n)H_(2n)—CH═CH₂ -nV—C_(m)H_(2m)—CH═CH—C_(n)H_(2n+1) -mVn —CH═CF₂ —VFF —OCO—CH═CH₂ —AC—OCO—C(CH₃)═CH₂ —MAC 3) Bonding Group —Z_(n)— Symbol —C_(n)H_(2n)— n—COO— E —CH═CH— V —CH═CHO— VO —OCH═CH— OV —CH₂O— 1O —OCH₂— O1 4) RingStructure —A_(n)— Symbol

H

B

B(F)

B(2F)

B(F,F)

B(2F,5F)

B(2F,3F)

B(2F,3CL)

B(2F,3F,6Me)

dh

Dh

ch

Cro(7F,8F) 5) Examples of Description Example 1 2-BB(F)B-3

Example 2 3-HHB(2F,3F)-O2

Example 3 V-HHB-1

Example 4 3-HDhB(2F,3F)-O2

Example 1

2-H1OB(2F,3F)-O2 (2-4) 3% 3-H1OB(2F,3F)-O2 (2-4) 10% 1V2-BB(2F,3F)-O2(2-5) 10% V-HHB(2F,3F)-O1 (2-7) 12% V-HHB(2F,3F)-O2 (2-7) 12%3-HH1OB(2F,3F)-O2 (2-10) 6% 2-BB(2F,3F)B-3 (2-11) 6% 3-HH-V (3-1) 25%3-HH-V1 (3-1) 6% 4-HH-V1 (3-1) 3% V-HHB-1 (3-5) 3% V2-HHB-1 (3-5) 4%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=80.1° C.; Tc<−20° C.;Δn=0.103; Δ∈=−3.9; Vth=2.09 V; η=20.7 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.1% byweight, and VHR-c of the resulting composition was measured.VHR-c=65.6%.

Comparative Example 1

VHR-c of the composition before adding compound (1-1) in Example 1 wasmeasured. VHR-c=34.7%.

Example 2

3-H1OB(2F,3F)-O2 (2-4) 8% V2-BB(2F,3F)-O1 (2-5) 4% V2-BB(2F,3F)-O2 (2-5)9% 1V2-BB(2F,3F)-O4 (2-5) 6% V-HHB(2F,3F)-O2 (2-7) 10% V-HHB(2F,3F)-O4(2-7) 3% 1V2-HHB(2F,3F)-O2 (2-7) 4% 3-HH1OB(2F,3F)-O2 (2-10) 12% 3-HH-V(3-1) 26% 1-HH-2V1 (3-1) 3% 3-HH-2V1 (3-1) 3% 5-HB-O2 (3-2) 3% 3-HHB-O1(3-5) 5% V-HHB-1 (3-5) 4%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=77.0° C.; Tc<−20° C.;Δn=0.099; Δ∈=−3.4; Vth=2.22 V; η=18.6 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.07% byweight, and VHR-c of the resulting composition was measured.VHR-c=63.4%.

Example 3

3-H2B(2F,3F)-O2 (2-3) 15% 5-H2B(2F,3F)-O2 (2-3) 12% 3-HHB(2F,3F)-O2(2-7) 8% 5-HHB(2F,3F)-O2 (2-7) 6% 2-HHB(2F,3F)-1 (2-7) 5%3-HBB(2F,3F)-O2 (2-15) 10% 4-HBB(2F,3F)-O2 (2-15) 6% 1V2-HBB(2F,3F)-O2(2-15) 4% 2-HH-3 (3-1) 20% 3-HH-4 (3-1) 10% V2-BB(F)B-1 (3-8) 4%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=80.0° C.; Tc<−20° C.;Δn=0.096; Δ∈=−3.4; Vth=2.19 V; η=19.0 mPa·s.

To the composition, compound (1-2) was added at a ratio of 0.1% byweight, and VHR-c of the resulting composition was measured.VHR-c=87.1%.

Example 4

3-H1OB(2F,3F)-O2 (2-4) 8% 3-BB(2F,3F)-O2 (2-5) 8% 2O-BB(2F,3F)-O2 (2-5)5% 2-HH1OB(2F,3F)-O2 (2-10) 8% 3-HH1OB(2F,3F)-O2 (2-10) 7%2-BB(2F,3F)B-3 (2-11) 8% 3-HDhB(2F,3F)-O2 (2-13) 10% 3-HH-V (3-1) 24%3-HH-V1 (3-1) 10% V2-HHB-1 (3-5) 9% 1O1-HBBH-4 (—) 3%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=83.7° C.; Tc<−20° C.;Δn=0.107; Δ∈=−3.7; Vth=2.21 V; η=22.9 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.05% byweight, and VHR-c of the resulting composition was measured.VHR-c=64.8%.

Example 5

V2-BB(2F,3F)-O2 (2-5) 12% 1V2-BB(2F,3F)-O2 (2-5) 5% 1V2-BB(2F,3F)-O4(2-5) 3% V-HHB(2F,3F)-O1 (2-7) 5% V-HHB(2F,3F)-O2 (2-7) 12%V-HHB(2F,3F)-O4 (2-7) 5% 3-HDhB(2F,3F)-O2 (2-13) 5% 3-dhBB(2F,3F)-O2(2-16) 4% 3-HH-V (3-1) 32% 1-BB-3 (3-3) 5% 3-HHEH-3 (3-4) 3% V-HHB-1(3-5) 3% 1-BB(F)B-2V (3-8) 3% 3-HHEBH-4 (3-9) 3%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=78.6° C.; Tc<−20° C.;Δn=0.107; Δ∈=−2.7; Vth=2.36 V; η=18.8 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.07% byweight, and VHR-c the resulting composition was measured. VHR-c=71.6%.

Example 6

V2-BB(2F,3F)-O2 (2-5) 12% 1V2-BB(2F,3F)-O2 (2-5) 6% 1V2-BB(2F,3F)-O4(2-5) 3% V-HHB(2F,3F)-O1 (2-7) 6% V-HHB(2F,3F)-O2 (2-7) 7%V-HHB(2F,3F)-O4 (2-7) 5% 1V2-HHB(2F,3F)-O4 (2-7) 5% 3-DhH1OB(2F,3F)-O2(2-14) 5% 3-dhBB(2F,3F)-O2 (2-16) 5% 3-HH-V (3-1) 26% 3-HH-VFF (3-1) 3%V2-HB-1 (3-2) 6% V-HHB-1 (3-5) 5% 2-BB(F)B-5 (3-8) 3% 5-HBB(F)B-3 (3-13)3%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=79.0° C.; Tc<−20° C.;Δn=0.112; Δ∈=−2.9; Vth=2.35 V; η=19.8 mPa·s.

To the composition, compound (1-2) was added at a ratio of 0.11% byweight, and VHR-c of the resulting composition was measured.VHR-c=65.1%.

Example 7

3-H1OB(2F,3F)-O2 (2-4) 10% 1V2-BB(2F,3F)-O2 (2-5) 10% V-HHB(2F,3F)-O1(2-7) 11% V-HHB(2F,3F)-O2 (2-7) 12% 3-HH1OB(2F,3F)-O2 (2-10) 9%2-BB(2F,3F)B-3 (2-11) 7% 3-HH-V (3-1) 26% 3-HH-V1 (3-1) 6% 1-HH-2V1(3-1) 3% 3-HHB-3 (3-5) 3% V-HHB-1 (3-5) 3%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=81.6° C.; Tc<−20° C.;Δn=0.103; Δ∈=−3.7; Vth=2.15 V; η=20.9 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.06% byweight, and VHR-c of the resulting composition was measured.VHR-c=62.2%.

Example 8

3-HB(2F,3F)-O2 (2-1) 8% 3-H1OB(2F,3F)-O2 (2-4) 8% 3-BB(2F,3F)-O2 (2-5)5% 2-HH1OB(2F,3F)-O2 (2-10) 8% 3-HH1OB(2F,3F)-O2 (2-10) 7%3-HDhB(2F,3F)-O2 (2-13) 10% 3-HH-V (3-1) 25% 3-HH-V1 (3-1) 10% V2-HHB-1(3-5) 11% 2-BB(F)B-3 (3-8) 8%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=79.4° C.; Tc<−20° C.;Δn=0.100; Δ∈=−3.5; Vth=2.20 V; η=19.5 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.05% byweight, and VHR-c of the resulting composition was measured.VHR-c=68.3%.

Example 9

V2-HB(2F,3F)-O2 (2-1) 5% 3-H2B(2F,3F)-O2 (2-3) 9% 3-HHB(2F,3F)-O2 (2-7)12% 2-HH1OB(2F,3F)-O2 (2-10) 7% 3-HH1OB(2F,3F)-O2 (2-10) 12%3-HDhB(2F,3F)-O2 (2-13) 3% 2-HH-3 (3-1) 27% 1-BB-3 (3-3) 13% 3-HHB-1(3-5) 3% 3-B(F)BB-2 (3-7) 3% 3-HB(F)HH-5 (3-10) 3% 3-HB(F)BH-3 (3-12) 3%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=78.9° C.; Tc<−20° C.;Δn=0.098; Δ∈=−2.9; Vth=2.34 V; η=18.2 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.03% byweight, and VHR-c of the resulting composition was measured.VHR-c=71.3%.

Example 10

5-H2B(2F,3F)-O2 (2-3) 9% 5-BB(2F,3F)-O4 (2-5) 5% 5-HHB(2F,3F)-O2 (2-7)3% V-HHB(2F,3F)-O2 (2-7) 6% 3-HH2B(2F,3F)-O2 (2-9) 3% 3-HH1OB(2F,3F)-O2(2-10) 13% 2-BB(2F,3F)B-3 (2-11) 3% 2-HHB(2F,3CL)-O2 (2-18) 3%4-HHB(2F,3CL)-O2 (2-18) 3% 2-HH-3 (3-1) 22% 3-HH-V (3-1) 5% V2-BB-1(3-3) 3% 1-BB-3 (3-3) 13% 3-HB(F)HH-5 (3-10) 3% 5-HBBH-3 (3-11) 3%3-HB(F)BH-3 (3-12) 3%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=78.9° C.; Tc<−20° C.;Δn=0.103; Δ∈=−2.6; Vth=2.49 V; η=17.6 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.05% byweight, and VHR-c of the resulting composition was measured.VHR-c=67.8%.

Example 11

3-H2B(2F,3F)-O2 (2-3) 20% 5-H2B(2F,3F)-O2 (2-3) 12% 3-HHB(2F,3F)-O2(2-7) 8% 5-HHB(2F,3F)-O2 (2-7) 6% 3-HDhB(2F,3F)-O2 (2-13) 5%3-HBB(2F,3F)-O2 (2-15) 10% 4-HBB(2F,3F)-O2 (2-15) 6% 2-HH-3 (3-1) 16%3-HH-4 (3-1) 13% 1V-HBB-2 (3-6) 4%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=76.2° C.; Tc<−20° C.;Δn=0.089; Δ∈=−3.6; Vth=2.12 V; η=19.8 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.03% byweight, and VHR-c of the resulting composition was measured.VHR-c=88.2%.

Example 12

3-HB(2F,3F)-O2 (2-1) 5% V-HB(2F,3F)-O4 (2-1) 4% 5-BB(2F,3F)-O2 (2-5) 6%3-B(2F,3F)B(2F,3F)-O2 (2-6) 3% V-HHB(2F,3F)-O2 (2-7) 10%3-HH1OB(2F,3F)-O2 (2-10) 10% 2-BB(2F,3F)B-3 (2-11) 5% 4-HBB(2F,3F)-O2(2-15) 5% V-HBB(2F,3F)-O2 (2-15) 7% 3-HBB(2F,3CL)-O2 (2-19) 3% 3-HH-O1(3-1) 3% 3-HH-V (3-1) 26% 3-HB-O2 (3-2) 3% V-HHB-1 (3-5) 7% 3-BB(F)B-5(3-8) 3%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=80.6° C.; Tc<−20° C.;Δn=0.114; Δ∈=−3.2; Vth=2.27 V; η=24.0 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.1% byweight, and VHR-c of the resulting composition was measured.VHR-c=61.2%.

Example 13

3-chB(2F,3F)-O2 (2-2) 6% 3-BB(2F,3F)-O4 (2-5) 6% V2-BB(2F,3F)-O2 (2-5)6% 3-HHB(2F,3F)-O2 (2-7) 5% V-HHB(2F,3F)-O1 (2-7) 6% V-HHB(2F,3F)-O2(2-7) 9% 2-HchB(2F,3F)-O2 (2-8) 3% 3-DhHB(2F,3F)-O2 (2-12) 5%3-HEB(2F,3F)B(2F,3F)-O2 (2-17) 3% 3-H1OCro(7F,8F)-5 (2-20) 3%3-HH1OCro(7F,8F)-5 (2-21) 3% 3-HH-V (3-1) 23% 4-HH-V (3-1) 3% 5-HH-V(3-1) 6% 7-HB-1 (3-2) 3% V-HHB-1 (3-5) 4% V-HBB-2 (3-6) 3% 2-BB(F)B-3(3-8) 3%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=70.9° C.; Tc<−20° C.;Δn=0.092; Δ∈=−3.2; Vth=2.16 V; η=22.9 mPa·s.

To the composition, compound (1-2) was added at a ratio of 0.15% byweight, and VHR-c of the resulting composition was measured.VHR-c=72.4%.

Example 14

5-H2B(2F,3F)-O2 (2-3) 9% 5-BB(2F,3F)-O4 (2-5) 5% 5-HHB(2F,3F)-O2 (2-7)3% V-HHB(2F,3F)-O2 (2-7) 6% 3-HH2B(2F,3F)-O2 (2-9) 3% 3-HH1OB(2F,3F)-O2(2-10) 13% 2-BB(2F,3F)B-3 (2-11) 3% 2-HHB(2F,3CL)-O2 (2-18) 3%4-HHB(2F,3CL)-O2 (2-18) 3% 2-HH-3 (3-1) 22% 3-HH-V (3-1) 5% V2-BB-1(3-3) 3% 1-BB-5 (3-3) 13% 3-HBB-2 (3-6) 3% 3-HB(F)HH-5 (3-10) 3%3-HB(F)BH-3 (3-12) 3%

The composition having a negative dielectric anisotropy was prepared,and characteristics thereof were measured. NI=76.1° C.; Tc<−20° C.;Δn=0.103; Δ∈=−2.6; Vth=2.47 V; r=16.8 mPa·s.

To the composition, compound (1-1) was added at a ratio of 0.05% byweight, and VHR-c of the resulting composition was measured.VHR-c=68.1%.

The compositions in Example 1 to Example 14 were found to have a largervoltage holding ratio after irradiation with ultraviolet light incomparison with the composition in Comparative Example 1. Therefore, theliquid crystal composition of the invention can be concluded to havefurther excellent characteristics.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the disclosure has beenmade only by way of example, and that numerous changes in the conditionsand order of steps can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention.

INDUSTRIAL APPLICABILITY

A liquid crystal composition of the invention satisfies at least one ofcharacteristics such as a high maximum temperature, a low minimumtemperature, a small viscosity, a suitable optical anisotropy, a largenegative dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat, or has asuitable balance regarding at least two of the characteristics. A liquidcrystal display device including the composition has characteristicssuch as a short response time, a large voltage holding ratio, a lowthreshold voltage, a large contrast ratio and a long service life, andtherefore can be used for a liquid crystal projector, a liquid crystaltelevision and so forth.

What is claimed is:
 1. A liquid crystal composition that has a negativedielectric anisotropy and a nematic phase, and contains at least onecompound selected from the group consisting of compounds represented byformula (1):

wherein, in formula (1), R¹ is hydrogen or alkyl having 1 to 15 carbons;R², R³, R⁴ and R⁵ are independently hydrogen or alkyl having 1 to 4carbons; ring A is phenyl or cyclohexyl; and a is 3 or
 4. 2. The liquidcrystal composition according to claim 1, containing at least onecompound selected from the group consisting of compounds represented byformula (1-1) and formula (1-2):


3. The liquid crystal composition according to claim 1, wherein a ratioof the compound represented by formula (1) is in the range of 0.005% byweight to 1% by weight based on the weight of the liquid crystalcomposition.
 4. The liquid crystal composition according to claim 1,containing at least one compound selected from the group consisting ofcompounds represented by formula (2) as a first component:

wherein, in formula (2), R⁶ and R⁷ are independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons or alkenyloxy having 2 to 12 carbons; ring B and ring D areindependently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene,1,4-phenylene in which at least one of hydrogen is replaced by fluorineor chlorine, or tetrahydropyran-2,5-diyl; ring C is2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene,2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diylor 7,8-difluorochroman-2,6-diyl; Z¹ and Z² are independently a singlebond, ethylene, methyleneoxy or carbonyloxy; b is 1, 2 or 3 and c is 0or 1; and a sum of b and c is 3 or less.
 5. The liquid crystalcomposition according to claim 4, containing at least one compoundselected from the group consisting of compounds represented by formula(2-1) to formula (2-21) as a first component:

wherein, in formula (2-1) to formula (2-21), R⁶ and R⁷ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons or alkenyloxy having 2 to 12 carbons.
 6. Theliquid crystal composition according to claim 4, wherein a ratio of thefirst component is in the range of 10% by weight to 90% by weight basedon the weight of the liquid crystal composition.
 7. The liquid crystalcomposition according to claim 1, containing at least one compoundselected from the group consisting of compounds represented by formula(3) as a second component:

wherein, in formula (3), R⁸ and R⁹ are independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons in which at least one ofhydrogen is replaced by fluorine; ring E and ring F are independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene or2,5-difluoro-1,4-phenylene; Z³ is a single bond, ethylene orcarbonyloxy; and d is 1, 2 or
 3. 8. The liquid crystal compositionaccording to claim 7, containing at least one compound selected from thegroup consisting of compounds represented by formula (3-1) to formula(3-13) as the second component:

wherein, in formula (3-1) to formula (3-13), R⁸ and R⁹ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which atleast one of hydrogen is replaced by fluorine.
 9. The liquid crystalcomposition according to claim 7, wherein a ratio of the secondcomponent is in the range of 10% by weight to 90% by weight based on theweight of the liquid crystal composition.
 10. The liquid crystalcomposition according to claim 4, containing at least one compoundselected from the group consisting of compounds represented by formula(3) as a second component:

wherein, in formula (3), R⁸ and R⁹ are independently alkyl having 1 to12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons in which at least one ofhydrogen is replaced by fluorine; ring E and ring F are independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene or2,5-difluoro-1,4-phenylene; Z³ is a single bond, ethylene orcarbonyloxy; and d is 1, 2 or
 3. 11. The liquid crystal compositionaccording to claim 1, containing at least one polymerizable compoundselected from the group consisting of compounds represented by formula(4):

wherein, in formula (4), ring G and ring J are independently cyclohexyl,cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl,1,3-dioxane-2-yl, pyrimidine-2-yl or pyridine-2-yl, and in the rings, atleast one of hydrogen may be replaced by halogen, alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbonsin which at least one of hydrogen is replaced by halogen; ring I is1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene,naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl,naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl,naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl,naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl,pyrimidine-2,5-diyl or pyridine-2,5-diyl, and in the rings, at least oneof hydrogen may be replaced by halogen, alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in whichat least one of hydrogen is replaced by halogen; Z⁴ and Z⁵ areindependently a single bond or alkylene having 1 to 10 carbons, and inthe alkylene, at least one of —CH₂— may be replaced by —O—, —CO—, —COO—or —OCO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH—,—C(CH₃)═CH—, —CH═C(CH₃)— or —C(CH₃)═C(CH₃)—, and in the groups, at leastone of hydrogen may be replaced by fluorine or chlorine; P¹, P² and P³are independently a polymerizable group; Sp¹, Sp² and Sp³ areindependently a single bond or alkylene having 1 to 10 carbons, and inthe alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO—or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or—C≡O—, and in the groups, at least one of hydrogen may be replaced byfluorine or chlorine; e is 0, 1 or 2; f, g and h are independently 0, 1,2, 3 or 4; and a sum of f, g and h is 1 or more.
 12. The liquid crystalcomposition according to claim 11, wherein, in formula (4), P¹, P² andP³ are independently a polymerizable group selected from the groupconsisting of groups represented by formula (P-1) to formula (P-6)

wherein, in formula (P-1) to formula (P-6), M¹, M² and M³ areindependently hydrogen, fluorine, alkyl having 1 to 5 carbons, or alkylhaving 1 to 5 carbons in which at least one of hydrogen is replaced byhalogen; when all of f pieces of P¹ and h pieces of P³ are a grouprepresented by formula (P-4), in formula (4), at least one of f piecesof Sp¹ and h pieces of Sp³ is alkylene in which at least one of —CH₂— isreplaced by —O—, —COO—, —OCO— or —OCOO—.
 13. The liquid crystalcomposition according to claim 11, containing at least one polymerizablecompound selected from the group consisting of compounds represented byformula (4-1) to formula (4-27):

wherein, in formula (4-1) to formula (4-27), P⁴, P⁵ and P⁶ areindependently a polymerizable group selected from the group consistingof groups represented by formula (P-1) to formula (P-3);

wherein, in formula (P-1) to formula (P-3), M¹, M² and M³ areindependently hydrogen, fluorine, alkyl having 1 to 5 carbons, or alkylhaving 1 to 5 carbons in which at least one of hydrogen is replaced byhalogen; in formula (4-1) to formula (4-27), Sp¹, Sp² and Sp³ areindependently a single bond or alkylene having 1 to 10 carbons, and inthe alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO—or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or—C≡C—, and in the groups, at least one of hydrogen may be replaced byfluorine or chlorine.
 14. The liquid crystal composition according toclaim 11, wherein a ratio of the compound represented by formula (4) isin the range of 0.03% by weight to 10% by weight based on the weight ofthe liquid crystal composition.
 15. The liquid crystal compositionaccording to claim 4, containing at least one polymerizable compoundselected from the group consisting of compounds represented by formula(4):

wherein, in formula (4), ring G and ring J are independently cyclohexyl,cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl,1,3-dioxane-2-yl, pyrimidine-2-yl or pyridine-2-yl, and in the rings, atleast one of hydrogen may be replaced by halogen, alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbonsin which at least one of hydrogen is replaced by halogen; ring I is1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene,naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl,naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl,naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl,naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl,pyrimidine-2,5-diyl or pyridine-2,5-diyl, and in the rings, at least oneof hydrogen may be replaced by halogen, alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in whichat least one of hydrogen is replaced by halogen; Z⁴ and Z⁵ areindependently a single bond or alkylene having 1 to 10 carbons, and inthe alkylene, at least one of —CH₂— may be replaced by —O—, —CO—, —COO—or —OCO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH—,—C(CH₃)═CH—, —CH═C(CH₃)— or —C(CH₃)═C(CH₃)—, and in the groups, at leastone of hydrogen may be replaced by fluorine or chlorine; P¹, P² and P³are independently a polymerizable group; Sp¹, Sp² and Sp³ areindependently a single bond or alkylene having 1 to 10 carbons, and inthe alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO—or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or—C≡O—, and in the groups, at least one of hydrogen may be replaced byfluorine or chlorine; e is 0, 1 or 2; f, g and h are independently 0, 1,2, 3 or 4; and a sum of f, g and h is 1 or more.
 16. The liquid crystalcomposition according to claim 7, containing at least one polymerizablecompound selected from the group consisting of compounds represented byformula (4):

wherein, in formula (4), ring G and ring J are independently cyclohexyl,cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl,1,3-dioxane-2-yl, pyrimidine-2-yl or pyridine-2-yl, and in the rings, atleast one of hydrogen may be replaced by halogen, alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbonsin which at least one of hydrogen is replaced by halogen; ring I is1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene,naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl,naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl,naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl,naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl,pyrimidine-2,5-diyl or pyridine-2,5-diyl, and in the rings, at least oneof hydrogen may be replaced by halogen, alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in whichat least one of hydrogen is replaced by halogen; Z⁴ and Z⁵ areindependently a single bond or alkylene having 1 to 10 carbons, and inthe alkylene, at least one of —CH₂— may be replaced by —O—, —CO—, —COO—or —OCO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH—,—C(CH₃)═CH—, —CH═C(CH₃)— or —C(CH₃)═C(CH₃)—, and in the groups, at leastone of hydrogen may be replaced by fluorine or chlorine; P¹, P² and P³are independently a polymerizable group; Sp¹, Sp² and Sp³ areindependently a single bond or alkylene having 1 to 10 carbons, and inthe alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO—or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or—C≡C—, and in the groups, at least one of hydrogen may be replaced byfluorine or chlorine; e is 0, 1 or 2; f, g and h are independently 0, 1,2, 3 or 4; and a sum of f, g and h is 1 or more.
 17. A liquid crystaldisplay device, including the liquid crystal composition according toclaim
 1. 18. The liquid crystal display device according to claim 17,wherein an operating mode in the liquid crystal display device includesan IPS mode, a VA mode, an FFS mode or an FPA mode, and a driving modein the liquid crystal display device includes an active matrix mode. 19.A liquid crystal display device having a polymer sustained alignmentmode, including the liquid crystal composition according to claim 11,wherein the polymerizable compound in the liquid crystal composition ispolymerized.